Vehicles having axially elongated, flexible-walled fluid-distensible ground contacting tires such as shown in U.S. Pat. No. 3,744,585 have been used in the past. Such vehicles are generally used on off-the-road sites and frequently encounter brush, tree limbs, and other obstructions. The vehicle tires are mounted on wheels by clamping the ends of the tires between a wheel flange and a keeper ring. In use, in rough terrains, the tire is sometimes damaged by obstructions jamming between the keeper ring and the ends of the tire. If this happens, the jamming increases with the tire rotation and results in the ends of the tire being torn with the result that the vehicle is disabled, frequently at a remote location.
Another disadvantage of tires now being used is that the very large tire is subjected to severe sidewall wear and tear. The tires are so large, for example they range up to 72 inches in diameter and 96 inches in width, that it is the tire that hits or rubs up against a passing object, the bed or frame of the vehicle being less in width than the tire; so it is desirable to protect the sidewall of the tire and protect the bead which is a most vulnerable section of the tire.
Additionally, while the elongated, flexible-walled low pressure tires (generally one to six psi pressure) have the advantage of a large ground contacting area by deforming and spreading out on the ground, because of their desirable flexibility their sidewalls are subjected to high stresses. That is, conventional tires incorporate multiple layers of fabric piles in the sidewalls which provides greater strength which protects the tire and overcomes axle torque, but results in a stiff tire with a low ground contact area. On the other hand, the elongated, flexible, low pressure tire of the type sold under the trademark Rolligon, has a minimum of plies in the sidewall in order to provide the desired flexibility. Because of this lack of sidewall stiffness, such tire will wind up when subjected to high axle torques. For example, the wheel will rotate as much as ten degrees before the tire starts rolling on the ground which causes spiral-like folds to occur in the sidewall, spiralling inward to the tire bead resulting in high stresses being imposed on the sidewall fabric at the bead. Such stresses shorten the tire life.
The present invention is directed to an improved tire for overcoming the drawbacks of the prior art.